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NATIONALSENIOR CERTIFICATEPHYSICAL SCIENCES: CHEMISTRY (P2)EXEMPLAR 2012MARKS: 150TIME: 2 hoursThis question paper consists of 15 pages, 1 data sheet, a periodic table and an answer sheet.INSTRUCTIONS AND INFORMATION
Write your name in the appropriate space on the ANSWER BOOK.
This question paper consists of NINE questions. Answer ALL the questions.
You may use a non-programmable calculator.
You may use appropriate mathematical instruments.
YOU ARE ADVISED TO USE THE ATTACHED DATA SHEETS.
Number the answers correctly according to the numbering system used in this question paper.QUESTION 1INSTRUCTIONS
Answer this question on the ANSWER SHEET. [NOTE: The ANSWER SHEET may either be a separate sheet provided as part of your question paper, or printed as part of the ANSWER BOOK.] Write your name in the appropriate space, if a separate ANSWER SHEET is used.
Various options are provided as possible answers to the following questions. Choose the answer and make a cross (X) in the block (A–D) next to the question number (1.1–1.10) on the ANSWER SHEET.
Do NOT make any other marks on the ANSWER SHEET. Any calculations or writing that may be necessary when answering this question should be done in the ANSWER BOOK and must be deleted clearly by means of a line drawn across the page.
If more than ONE block is marked per question, no marks will be awarded for that answer.PLACE THE COMPLETED ANSWER SHEET INSIDE THE FRONT COVER OF THE ANSWER BOOK, IF A SEPARATE ANSWER SHEET HAS BEEN USED.EXAMPLE:QUESTION: The SI unit of time is .
[NOTE: This layout may vary, depending on the type of ANSWER SHEET used by the
Caffeine is a compound found in coffee beans. The diagram below shows a chromatogram of caffeine and four different drinks, A to D.
Caffeine A B C D
Which ONE of the above drinks contains caffeine?
Natural nitrogen occurs as the two isotopes 14N and 15N.
How many different types of nitrogen molecules will occur in air as a result of the combination of the above atoms?
In which ONE of the following compounds do BOTH ions have the same electron configuration as argon?
When an atom X of an element in Group 1 reacts to become X+, the …
number of filled energy levels decreases.
In which ONE of the following does 'energy' represent the first ionisation energy of sodium?
The correct chemical formula for potassium permanganate is …
The number of atoms in ONE formula-unit of copper(II)sulphate (CuSO4) is …
Which ONE of the following represents one mole of gas at STP?
Which ONE of the statements below is CORRECT?
2 molecules of hydrogen gas react with 1 atom of oxygen gas to form2 atoms of water vapour.
4 atoms of hydrogen gas react with 2 molecules of oxygen gas to form 2moles of water vapour.
2 moles of hydrogen gas react with 1 mole of oxygen gas to form2 moles of water vapour.
4 g of hydrogen gas react with 16 g of oxygen gas to form 18 g of watervapour.
the layer of rock found above the earth's mantle.
the hot liquid rock located in the earth's outer core.
the very dense rock located in the earth's inner core.
all the water below, on and above the surface of the earth.ANSWER QUESTIONS 2–12 IN THE ANSWER BOOK.INSTRUCTIONS AND INFORMATION
Start EACH question on a NEW page in the ANSWER BOOK.
Leave ONE line between two subquestions, for example between QUESTION2.1 and QUESTION 2.2.
Number the answers correctly according to the numbering system used in this question paper.
Show ALL formulae and substitutions in ALL calculations.
Round off your FINAL numerical answers to a minimum of TWO decimal places.
Give brief motivations, discussions, et cetera where required.QUESTION 2 (Start on a new page.)
Choose an item from COLUMN B that best matches a description/item in COLUMN A. Each item in COLUMN B may be used only ONCE. Write only the letter (A–G) next to the question number (2.1.1–2.1.7) in the ANSWER BOOK.
Solid carbon dioxide is sometimes known as dry ice. Under normal circumstances dry ice sublimes as it warms up.
When you take a block of butter out of the fridge, it is hard. However, after 15 minutes at room temperature it is soft enough to spread.
Use the kinetic theory to explain the above observation.QUESTION 3 (Start on a new page.)
The heating curve for a pure substance at atmospheric pressure is shown in the graph below.
Write down the following for this pure substance:
Is this pure substance water? Give a reason for the answer.
What is the physical state of the substance at:
Point X shown on the graph
What happens to the temperature while the substance melts? Explain this observation.QUESTION 4 (Start on a new page.)
Sodium reacts with chlorine to form sodium chloride, a substance used in all households.
Write down its number of valence electrons
Represent the formation of sodium chloride from sodium and chlorine with the aid of Lewis diagrams.
Name the type of crystal lattice of which sodium chloride is an example.
A chlorine atom can also bond to another chlorine atom to form a molecule.
Name the type of bond that forms between TWO chlorine atoms.
Represent the chlorine molecule with a Lewis diagram.QUESTION 5 (Start on a new page.)
Information of six elements, represented as P, Q, R, S, T and Y, are given in the table below.ELECTRON STRUCTURE
Which element (P, Q, R, S, T or Y):
Two of the above elements are in the same group of the periodic table. Write down:
The letters representing these TWO elements
ONE of the elements represented above is calcium. Write down the:
Flame colour that would be produced by calcium salts
Write down the formula of the compound formed by the combination of elements:
Identify element T and write down its A X notation.
Another element, X, occurs in nature as two isotopes, X-23 and X-25. The drawing shown below represents a sample of this element.
Use the above information to calculate the relative atomic mass of element X.QUESTION 6 (Start on a new page.)
The unbalanced equation (i) and the word equation (ii) for two chemical reactions are shown below.
&DOFLXP FDUERQDWH ĺ FDOFLXP R[LGH FDUERQ GLR[LGH
Which ONE of the above equations (i or ii) represents a:
What does (g) represent in equation (i) above?
Write down a balanced chemical equation for the word equation (ii). Show the phases of ALL reactants and products.
Rewrite equation (i) in the ANSWER BOOK and balance the equation.
Name the chemical law that a balanced equation illustrates.
Using equation (i) above, show that mass is conserved during the reaction.QUESTION 7 (Start on a new page.)
The arrangement below is used in a class to investigate the conductivity of a solution. 7KH EHDNHU LV LQLWLDOO\ ILOOHG ZLWK PƐ GLVWLOOHG ZDWHU ,W LV REVHUYHGthat the bulb does not glow.
Give a reason why the bulb does NOT glow.
A 15 g sample of ammonium nitrate is now dissolved in the distilled water. It is observed that the bulb glows brightly.
Write down the general name given to an aqueous solution that conducts electricity.
Write down the formulae of the ions present in this solution.
Calculate the concentration of the ammonium nitrate solution.
Learners are given two bottles labelled A and B. It is known that one bottle contains a MgSO4 solution and the other one contains a %D&Ɛ2 solution.
They pour a sample from bottle A into a test tube and perform two tests to identify its contents. They record their findings in the table below.OBSERVATION
sample from bottle A in a test tube.Add a few drops of dilute nitric acid (HNO3)
Write down the NAME and FORMULA of the white precipitate that forms in the test tube.
Give a reason why it is necessary to add nitric acid to the contents of the test tube after the white precipitate forms.
Which bottle (A or B FRQWDLQV WKH %D&Ɛ2 solution?
The learners now pour a sample from each of bottles A and B into two separate test tubes and then mix the contents of the two tests tubes. They observe a white precipitate.
Write down a balanced equation for the reaction that takes place in the test tube after mixing the two samples. Show ALL phases of reactants and products.
Name the type of reaction that takes place.QUESTION 8 (Start on a new page.)
The reaction between magnesium and dilute hydrochloric acid is represented by the balanced equation below.
0JV +&ƐDT ĺ 0J&Ɛ2(aq) + H2(g)
During an experiment, 1,5 g of magnesium reacts with excess dilute hydrochloric acid to produce hydrogen gas at STP.
Volume (in dm3) of hydrogen gas produced at STP
Mass (in gram) of 0J&Ɛ2 produced (4)
1XPEHU RI FKORULQH DWRPV SUHVHQW LQ WKH 0J&Ɛ2 produced
The molar mass of hydrated sodium carbonate is found to be 268 gÂPRO-1. The formula of the hydrated sodium carbonate is Na2CO3.xH2O.
Calculate the number of moles water of crystallisation (x) in the compound.
The empirical formula of a certain compound is to be determined. On analysis of a sample of the compound it was found to contain
Define the term empirical formula.
Determine the empirical formula of the compound. Show ALLcalculations.QUESTION 9 (Start on a new page.)
Two-thirds of our planet is covered with water. Much of the water is found in lakes, rivers and oceans. Water also occurs underground.
The diagram below shows how water is constantly recycled on earth.Process BWater vapourProcess CProcess APrecipitationSurface runoffInfiltrationReservoirUnderground water
Due to industrialisation, acid rain is common in certain areas.
A laboratory technician tests the acidity of three water samples collected during precipitation. The results obtained are shown in the table below.
Which ONE of the samples (1, 2 or 3) is NOT safe for human consumption? Give a reason for the answer.
Sulphur dioxide is one of the gases responsible for acid rain. Write a balanced equation for the reaction that takes place when sulphur dioxide dissolves in water to form sulphurous acid.
State ONE negative effect of acid rain on the environment.
Chlorine is used during water purification. However, in large amounts chlorine can be harmful for human consumption.
Give a reason why chlorine is added to drinking water.
A certain compound X is acidified with nitric acid and added to a water sample to test for the presence of chlorides in the water. A white precipitate forms.
Write down the NAME or FORMULA of compound X.DATA FOR PHYSICAL SCIENCES GRADE 10PAPER 2 (CHEMISTRY)GEGEWENS VIR FISIESE WETENSKAPPE GRAAD 10VRAESTEL 2 (CHEMIE)TABLE 1: PHYSICAL CONSTANTS/TABEL 1: FISIESE KONSTANTESTABLE 2: FORMULAE/TABEL 2: FORMULESVAN ELEMENTEPERIODIEKE TABEL : DIE aTABEL 3Simbooloommassat atomic maiewe tomic numberAtoomgetallateBLE OF ELEMtiwiteitproximate relativnaderde raeBSLEUTELElektronegBLE 3: THE ANSWER SHEETLEARNER'S NAME:

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